BRCA1 and cancer: To date, several small-molecule PARP1 inhibitors, such as Olaparib, Rucarparib, Niraparib, and Talazoparib, have been approved for the treatment of BRCA-mutation ovarian and breast cancers.391 However, there are still challenges in terms of PARP1 inhibitors usage that limit their therapeutic utility, including the acquisition of drug resistance, the low proportion of BRCA1 or BRCA 2 mutations in cancer cells, and cytotoxicity caused by PARP1 trapping.392,393